How to check if a client device supports 802.11v
This post is directly related to the following previous article: “Wireshark: How to check it a Wi-Fi Network Supports 802.11v“.
In the previous article, we talked about how to check if a specific Wi-Fi network is supporting IEEE 802.11v, from the access point perspective. Like anything in Wi-Fi, we need support from both the access point and the STAs in order for it to work.
So in this article, we are going to explain how we can validate is a specific client device supports 802.11v.
I would like to address special thanks to Phil Morgan for providing useful information and giving me the idea to write this follow up post.
Note: before we start looking deeper into the association request frame, something important needs to be noted regarding 802.11v client support. Since the support of 802.11v is advertised by the AP in the beacon frames the station will be aware of 802.11v support within the BSS and will only advertise its support for 802.11v in its association request if it is advertised by the AP in the beacon frame.
So if you are performing your own packet captures, make sure you enable 802.11v support on the access point first.
Once again, looking at the association request frame in order to find 802.11v support, we need to focus on the Extended Capabilities Information Element number 127 and look at the 4th bit of the 3rd octet. This bit is most commonly named the “BSS Transition bit“. If the bit is set to “1“, the client device support 802.11v.
Make sure to read the note at the bottom of the page related to IEEE 802.11v support.
VALIDATE CLIENT 802.11V SUPPORT ON A CISCO WLC
On a Cisco Wireless LAN Controller, there is a way to check if an associated client supports IEEE 802.11v. Obviously, as explained earlier, this client device has to be associated to an SSID already advertising the BSS transition capability.
Click on the mac address of the client that you want to study. This will open up a new page providing more detailed information related to this specific client.
On this page, you will be able to see if it support IEEE 802.11v, as shown below, under the “802.11v BSS Transition” sub-section:
UPDATE (2019): USING THE WLAN PI AND PROFILER
Thanks to our amazing Wi-Fi community, we now have tools to validate the general capabilities of Wi-Fi client devices in an easier and more scalable way.
This program broadcast a special beacon frame that tricks the client device in thinking that the Wi-Fi network supports pretty much everything and is using the maximum capabilities defined in the 802.11 specifications.
# capture frames on channel 44 using an SSID called 'TEST' wlanpi@wlanpi:/home/wlanpi/profiler# sudo python ./profiler.py -c 44 -s "TEST"
Then, you can simply use your device and connect to that specific SSID. The client will not hold back and provide, in return, its maximum capabilities (including 802.11v).
(Image from the github documentation page)
You can also use the GUI of the WLAN Pi to retrieve the results in a text or csv file.
The profiler tool would require an entire dedicated blog article and does way more than just validate 802.11v. I invite you to check it out and try it out yourself.
Thank you for reading!